From: Simon Horman <horms@verge.net.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "kexec@lists.infradead.org" <kexec@lists.infradead.org>,
Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH] kexec: crash: don't save swapper_pg_dir for !CONFIG_MMU configurations
Date: Wed, 29 Feb 2012 10:32:57 +0900 [thread overview]
Message-ID: <20120229013257.GG6013@verge.net.au> (raw)
In-Reply-To: <20120228124554.73b4f051.akpm@linux-foundation.org>
On Tue, Feb 28, 2012 at 12:45:54PM -0800, Andrew Morton wrote:
> On Tue, 28 Feb 2012 09:40:57 +0000
> Will Deacon <will.deacon@arm.com> wrote:
>
> > > > Still, you didn't answer my question! What effect will the absence of
> > > > SYMBOL(swapper_pg_dir)= have upon downstream tools? If "none" then
> > > > sure, let's remove it. If "explosion" then we should emit a dummy
> > > > SYMBOL(swapper_pg_dir)=0 if CONFIG_NOMMU.
> > >
> > > My thought was that the tools wouldn't be used in the CONFIG_NOMMU case (yet).
> > > But I take your point and I think the answer is that the fallout is unknown.
> > > Emitting a dummy value as you suggest seems reasonable.
> >
> > The reason I didn't choose a dummy value to start with is because there are
> > plenty of other fields in the dump that are predicated on build-time CONFIG
> > options. Admittedly, some of these appear to be tagged with length
> > information, but consider these guys:
> >
> > #ifndef CONFIG_NEED_MULTIPLE_NODES
> > VMCOREINFO_SYMBOL(mem_map);
> > VMCOREINFO_SYMBOL(contig_page_data);
> > #endif
> >
> > Since the VMCOREINFO_SYMBOL macro stringifies the identifier, I guess userspace
> > has to treat the whole thing as a map, meaning that we *can* safely remove
> > elements from it.
> >
> > So that's my speculation. Maybe somebody on the kexec list can confirm?
>
> Yeah, I do think the chance of breaking anything here is small, and in
> the unlikely event that something *does* break then a) it deserved to
> break ;) and b) the user of that app will be a developer who can
> unbreak it.
>
> Let's run with the patch as-is.
Fine by me :)
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prev parent reply other threads:[~2012-02-29 1:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-24 14:40 [PATCH] kexec: crash: don't save swapper_pg_dir for !CONFIG_MMU configurations Will Deacon
2012-02-25 2:37 ` Simon Horman
2012-02-26 22:58 ` Will Deacon
2012-02-27 0:37 ` Simon Horman
2012-02-27 19:30 ` Will Deacon
2012-02-27 23:52 ` Simon Horman
2012-02-27 23:56 ` Andrew Morton
2012-02-28 0:19 ` Simon Horman
2012-02-28 0:26 ` Andrew Morton
2012-02-28 0:51 ` Simon Horman
2012-02-28 1:25 ` Andrew Morton
2012-02-28 1:35 ` Simon Horman
2012-02-28 9:40 ` Will Deacon
2012-02-28 20:45 ` Andrew Morton
2012-02-29 1:32 ` Simon Horman [this message]
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